Rapid Ultrastructural Changes in the CA3 Field of Hippocampus of Krushinskii-molodkina Rats after Acoustic Stress

摘要

Morphometric analysis of electron microphotographs of hippocampus of Krushinskii-Molodina rats with hereditary predisposition to audiogenic epilepsy revealed rapid reversible changes in synapses between terminals of mossy fibers and dendritic spines of pyramidal neurons in the fields CA3 after convulsions induced by stressing auditory effects. It was established that an initial increase of the number, size, and perforation of active zones, which indicates activation of synaptic transmission, was subsequently replaced by a decrease of these parameters as well as of spine invaginations and by an increase of the number of dense-core synaptic vesicles in active zones of synapses. Previous administration of melatonin was observed to lead to a significant decrease of intensity of manifestation of the convulsion symptoms and of the degree of the above ultrastructural changes, which might be considered an evidence for melatonin sedative and stress-limiting, as well as anti-epileptic and neuroprotective properties.